Hot cathode electron discharge tube



1931- SUTHERLIN HOT CATHODE ELECTRON DISCHARGE TUBE Filed Aug. 14, 1926 INVENTOR Z 96 Su/erfih.

WITNESSES:

ATTORNEY Patented Oct. 27, 1931 UNITED STATES eATENr oFFlcE LEE SUTHERLIN, OF EAST PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA HOT CATHODE ELECTRON DISCHARGE TUBE Application filed August 14, 1926.

My invention relates to hot-cathode-electron-discharge tubes of the type utilizing cathodes in the shape of filamentary ribbons and, among the objects of the invent-ion is the provision of an improved mounting or support for such ribbons, whereby better and more uniform tube operation is obtained.

In many types of radio-receiving tubes designed to give a large output sufficient to oply no attention has been given to the way in which the plane of the ribbon filament was related to the adiacent surfaces of the plate, so that. in general. parts of the filament had their edges exposed to the plate surfaces while other parts had their fiat sides exposed thereto. It is clear that this haphazard manner of mounting the filament not only affects the uniformity of the tubes so made, but it also is bound to unnecessarily increase the plate impedance. inasmuch as the major portion of the electrons which are emitted from the large flat ribbon surfaces have to take a curved path on their way to the plate.

According to mv invention. a better and more uniform tube is provided by taking care that. the flat sides of the filamentary ribbon shall be exposed toward the plate surfaces for substantially the entire length thereof.

In the accompanying drawings Figure 1 is an enlarged perspective view of Serial No. 129,121.

Fig. 5 is a horizontal cross-sectional view on line VV of Fig. 1.

Referring to Figs. 1, 2 and t of the drawings, which show a preferred embodimentof my invention, a radio-receiving tube comprises a glass envelope 1 having, at its bottom, a re-entrant stem 2 terminating in a flat press 3, into which are fused a plurality of lead-in and supporting wires referred to hereinafter.

Directly above the press 3 and substantially in the same plane therewith, is mounted a cathode in the form of an inverted W- shaped' ribbon 5, .the two upper bights thereof being supported by a pair of spring hooks 6 which are secured to a pair of supporting rods 7. which are held in spaced relation by a glass bead 8 that is fused around the upper end of a carrier rod 9,.the lower end of which is offset'and fused into the center of the press.

The support for the two ends of the filament-and the electrical connection for sending current therethrough is provided by a pair of lead-in wires 11 fused into the press on both sides of the central carrier rod 9, the upper ends of the lead-in wires being bent outwardly to terminate approximately at the points where the ends of the filament are to be held. The lower middle bight of the filament is held by an additional hook 152, which is secured to the offset carrier rod 9 near its lower end,.where it is fused into the press 3.

The two loops of the W-shape cathode filament 5 are surrounded by an oval-shape plate or anode 15 having extended flat sides 16 which are substantially parallel to the plane of the filament loops.

In spaced relation from the filament loops 5 and the plate 15 and interposed therebetween, is a grid helix 17 which is of oval shape, conforming substantially to the shape of the plate 15.

The plate 15 and the grid 17 in the interior thereof, are insulatingly supported and spaced by means of two pairs of supporting wires 18 and 19, respectively. the left-hand anode-supporting wire and the right-hand grid-supporting wire constituting also the lead-in connections thereto, respectively.

40 necessary to obtaintheiimproved mounting As stated above, I have found that the performance of the tube will vary within relatively wide limits, depending on whether the edge or the flat side of the filamentary cathode ribbon is exposed to'the adjacent" anode surfaces. Accordingly, the tubes of the above-described charactenas manufac tured heretofore, varied greatly in their characteristics, a fact which greatly perplexed those responsible for thedesign and active lengths with theirnfia t sides facing the adjacentflat plate surfaces.

- The 1 actual structural'changes necessary to obtain the improved cathode mounting arefivery small, although, as pointed out;

, above, the resulting effect is. very material.

-Thus,'in:the prior-art'tubeaithe two extreme ends of the W-shaped filament ribbon were secured or fastened to the outwardly bent ends of the le ad in wiresll in substantially.

thesame' way as is show'n in the drawings, that is, with the flat sides of. the ribbon dis-1 posed parallel to the flat sides of the anode. I r- The plane of the hooks 6; and:12,"which support the upper and lower bights: of thefilainent, in: the prior' art tubes, were 'usually perpendicular to the plane of the filament loops, so that the middle'V of the filament loop had its edges" exposed toward theadjacent sides of the plate while thetwoupper endsof the loop were disposed edgewise and theirlower ends were disposed fiatw-is'elwith respect to the plate-surface." All that was of the filament, as described hereinbefore, Was to changethe. plane of the hooks 6 and 12 which support the upper andlower bights' ofthe filament loop. v 7

To this end, the hook portion 20 at the end. of the upper hook 6 of the prior=art hook has been turned 90 sidewise so that the hook, as

- shown in the drawings, now liesin the plane of the filament loops.-

, Similarly, the hook 12, which holds the lower bight of the filament is now mounted in the plane of the filamentloop. With the changed location of the planes of the hooks, the filament ribbon -5 is. now-wound so that the edges of the'filar ment are always disposed in the'direction of the filament loop while the flat'si desareexposed'toward the flat sides of the plate surfaces on both sides thereof.

, It is, of course, ,clear:that my invention. is not restricted to "the particular arrangement and details of construction shown" in the preferred embodiment-described above;

7 One of the ideas underlying my invention,

namely, the means of ensuring tubesof uniform characteristics may, for instance, be applied without, at the same time, applying the idea of securing lower plate impedance.

tube-of such construction would merely have the filament wound edgewise PQI'PBIICllCU-' larly 'to the' plane of the filament loops throughout its entire length. In such case, the plane of the filament hooks will be the sameas described hereinabove in connection with the prior-art tubes, the only change'required being to turn the plane in which the two extreme ends of the filament ribbon are supported on the lead-in wires 11. Such an arrangementof filament support is shown out substantially'the entire active length of said filament. I 1 s 1 2. In a hotcathode -electron discharge tube, a filamentary cathode ribbon, a tubular anode surrounding said ribbon and having opposing fiat faces separated by distance greater than thezwidth of said ribbon, and meansfor so supporting said cathoderibbon that the flat sides thereof are exposed to and parallel with. said flat faces of the anode.

3; In a hot -i cathode electron discharge tu'be,a filamentary cathode ribbon,- atubular anode surrounding said ribbon and having narrow and wide sides corresponding substantially in configuration to the edge and flat sides of theribbon, its narrow sides being greater than'the width of said ribbon, and means for so supporting said' cathode ribbon that its fiatsides are exposed throughout substantially their entire active length parallel to the wide sidesof said anode.

' 4. In a hot cathode electron discharge tube, an anode comprising a member having substantially flat extended-surfaceportions, a filamentary cathode ribbon constituting a loop in a planeparallel to said flat anode surfaces,and means for so supporting said loop that the flat, sides of the ribbon are exposed throughout {substantially their entire active length to the flat surface'portions of said anode. v I V h 5 .In a hot-cathodeelectron-discharge tube, a. substantially flattened tubular anode inember'having relatively large parallel opposing active surface portions, a filamentary cathode ribbon constituting a loop disposed in aplane substantially midway betweensaid parallel-surface portions, and means forso supporting said filament that'the fiat sides thereof lie in planes parallel to the plane of the loop.

6. In an electron-discharge tube, a tubular fiat anode, a filament ribbon constituting a loop disposed in a central plane within said anode parallel to the fiat sides thereof, means for supporting the upper bight of said loop comprising a carrier rod extendin outside said anode, a spring arm supported by said carrier rod and extending to above said bight the end of said spring arm constituting a hook for supporting the filament bight, said hook being disposed substantially in the plane of said loop, and means for so supporting the lower ends of said filament that the flat sides thereof are parallel to the plane of the loop.

7. In an electron-discharge tube, an inverted v'-shaped loop of a filamentary cathode ribbon having flat sides held with its flat sides substantially in a plane, a tubular anode having flattened sides surrounding said cathode ribbon and having said sides parallel to said plane.

8. In a hot cathode -electrondischarge device, a cathode comprising a filamentary ribbon so flatwise folded upon itself that the two legs diverge and constitute a substantially V-shape loop lying substantially in the plane of the flat ribbon sides.

9. In a hot cathode electron discharge device, a cathode comprising a filamentary ribbon so fiatwise folded upon itself that the two legs diverge and constitute a substantial- V-shape loop, and a wire portion so supporting the fold of said ribbon that the two ribbon sides lie fiat in the plane of the loop.

In testimony whereof, I have hereunto subscribed my name this 11th day of August, 7 1926. LEE SUTHERLIN. 

